Improvement in reverberatory furnaces for roasting ores



2 Sheets--Sheet1.

1.0. STEWART. Re'verheratory Furnaces for Boasting Ores, 81c.

Patented March 3. 1874.

1 c H n 7 m N H W I// /d LV/// m n w m u u H] a a I n m H- 7r. 21 A HM c 1 c n :2 7

IIIIIIF 2 Sheets--Sheet 2e 1. 0.8TEWARY. Beverberatory Furnaces for Boasting Ores, 8w. N0,]48,096, PatentedMarch 3.1874.

Mae/mew 612g Orrron.

JAMES O. STEWART, OF GEORGETOWN, COLORADO TERRITORY.

IMPROVEMENT IN REVERBERATORV FURNACES FOR ROASTING ORES, &c.

Specification forming part of Letters Patent No. h 1,096 dated March 3, 1874; application filed January 15, 1874.

To all whom it may concern:

Be it known that I, J. OSCAR STEWART, of Georgetown, county of Clear Creek, Territory of Colorado, have invented a new and useful Improvement in Reverberatory Furnaces for toastin g, Desulphurizin g, or Ohloridizing Ores and Minerals or metallic products; and I do hereby declare that the followingis a full, clear, and exact description thereof, reference being bad to the accompanying drawings, making part of this specification, in which- Figure 1, Plate I, is a vertical longitudinal section of my improved furnace, constructed with three roasting or treating chambers in communication with one another. Fig. 2 is a horizontal section of the same in the line as m of Fig. 1. Fig. 3 is a vertical transverse section in the line 1 3 of Figs. 1 and 2. Fig. 4 is a cross-section in the line a z of Fig. 1. Fig. 5 is a similar section in the line 2 z of Fig. 1. Figs. 6 and 7 are perspective views of the upper and under sides of the combined cylindric and spherical top or arch of the roasting or treating chambers. Fig. 8 is a longitudinal section of my improved combined cylindric and spherical top applied to a furnace with a single roasting or treating chamber, the sec tion being in the line to w of Fig. 9. Fig. 9 is a horizontal section of the same. Fig. 10 is a cross-section in the line as x of Figs. 1 and 2. Fig. 11 is a similar section in the line y 3 of Figs. 8 and 9.

My invention is designed for that class of reverberatory furnaces which is adapted for roasting, desulphurizin g, or chloridizing ores, minerals, or metallic products.

The nature of my invention consists, first, in varying the length and width of the roasting or treating chambers of each furnace relatively, and combining with the same an arch or crown, which is in form of a segment of a hollow sphere, where it overhangs or covers the first hearth of the roasting-chamber, and in form of a segment of a cylinder where it overhangs or covers a second, or a second and third, hearth of said chamber. This construction, as will hereinafter be made to appear, enables the operator to utilize the heat in a more proper manner and to a greater extent than can be done with other forms of furnace tops or crowns in use. It consists, second, in

combining an elevated furnace in a peculiar manner with one or more low-down furnaces, so that an auxiliary fire-box is employed, from which heat passes over a hearth, which is underneath the flue which connects the l er furnace with the upper furnace.

By this arrangement, as will hereinafter be made to appear, a fresh supply of heat to the ore is provided at a point where the main-furnace heat is losing its temperature, and this fresh heat, combining with the heat from the main furnaces, heats the charge of ore which is on the hearth directly adjoining the auxiliary fire-box, and, passing through the flue to the upper furnace, is sufficient to ignite and keep the sulphur burning in the ores of said furnace. Thus all the heat is utilized to the best advantage, and hence the expense for fuel reduced. Labor is also saved, inasmuch as the ore can be very expeditiously handled or moved from hearth to hearth.

The construction of the crowns, together with the combination of furnaces, enables the operator to roast a greater number of tons of material in a given time than has heretofore been accomplished with furnaces with which over to the front wall of said furnace, and also made to unite with an extension or bulging front portion, A, of said furnaces, as shown. The portion of the furnace A which extends over the meeting ends of the furnaces A A forms a fine, 0, which connects with the firebox 13 which is just in rear of the meeting ends of the furnaces A A, as shown. The

furnaces A A have hearths a a and the furnace A hearths a a as shown. The hearth a is considerably broader than the hearth a, and consequently the walls upon which the crowning portion of this hearth rests are set farther apart. The hearth a is nearly square,

while that of a is oblong. The part a of the furnace is crowned with an arch, 0, which presents the form of a segment of a hollow sphere, while the part a is crowned with an arch, 0 which is in the form of a segment of a cylinder. This combination crown is shown clearly in Figs. 6 and 7 of the drawings. At the point where the flue of the auxiliary fire-box is employed the bulged-out portion of the front wall of the main furnace or furnaces is connected to the fine-wall by means of a crown, 0 which is a segment of a hollow sphere. D D are the draft-fines, and E E E the workdoors to the hearths of the furnace, and 9 stops between the hearths.

In Figs-8 and 9 the same construction of furnace in all respects to the one just described is maintained, except that only one roastingchamber, A, with its own fire-box and draftfiues D, is adopted in the erection and working of the furnace. This single furnace may have three hearths like those a a and in that case the cylindric portion of the crown will be double the length of the spherical portion, and another step like y will be constructed between the two hearths which come under this cylindric arch.

To facilitate the description, I will first describe the operation of the single furnace, Figs. Sand 9, and I shall speak of it as having three working hearths instead of two. Acharge of ore being placed upon the third hearth which is nearest the draft-flue, the sulphur begins to ignite, and, after aboutthree hours stirring, is moved upon the hearth (d, or No. 2,by means of spades or hoes through the back and front side work-doors. Another charge of ore is now placed upon the vacated hearth just referred to. The ore on both hearths is stirred for about three hours more, when it is found that ore on hearth a is nearly desulphurized--that is, the raw sulphur has been burned out, and the metals, having taken up oxygen from air admitted to the furnace through the fire-box and work-doors, are formed into sulphates, so that the ore has changed its color, and gives off a light sulphurous-acid odor. This charge of ore,then, on the hearth a is moved forward, as before stated, to hearth a, or No. 1, and the ore on hearth No. 3 (not shown) is moved to hearth a, or No.2, and a new charge of ore takes its place. As soon as these manipulations are ended, about four to ten per cent. of common salt is thrown in and intimately mixed with the ore 011 the hearth No. 1, and, as the sulphuric or sulphurous acid present does decompose the salt, the chlorine is liberated fronrthe salt, which chlorine, in part, is absorbed by the metals present, such as gold, silver, and a portion of lead, zinc, and iron, formed into chlorides of these metals. Just for this reason the ore must be at a good heat, above a high red heat,

but not to a white heat, and at the same time it is of the utmost importance that a large supply of fresh undecomposed air be admitted to this ore on this hearth a, in order to get rid of the last traces of sulphurous acid; and to acco:n plish this chemical reaction I have found the arch, with the peculiar combination of spherical and cylindric form, to be very important, because it admits (by being highly curved over the hearth a) of a'large'full fire, so that plenty of cold air can be used and stillnot chill the charge on the hearths beyond this first charge; and, at the same time, while such heat under any other shaped crown to the hearth a would sinter or bake and spoil the ore on hearth a; this allows the heat to pass along this crown to the transverse or cylindric crown, with which it is combined and united, where the heat is depressed down upon hearth a and the hearth No. 3 (not shown) without being chilled by the admission of so much air to the ore on the hearth a. When all the charges of ore are stirred about three hours from the time of moving the ore on hearth a, it is found that this last-mentioned ore has become chloridized, having changed its color again and become spongy or woolly, and it gives off a sweet chlorine smell. It is now withdrawn from the furnace and the manipulation continues as before stated.

The relative proportions of the hearths of the furnace, whose operation has been just described, may be as follows Hearth a, 9 x 9 in clear; hearth a 8 x 10 in clear and hearth .referred to as No. 3, but not shown, 8 x 12 in clear.

The operation of the combined furnace, Figs. 1, 2, and 3, is asfollows: The ore isadmitted on the last hearth c of the elevated furnace; it is stirred for an hour or an hour and a half; the sulphur here ignites ason hearth No. 3 of single furnace; the charge is then moved forward to the hearth a and a new charge takes the place of it. Both charges are stirred about one hour and a half, or less, and the charge on this second hearth is drawn down upon the hearth in the lower furnace Where the auxiliary fire is located, and the charges in the elevated furnace proceed as before. iliary fire having lost a large portion of its sulphur before it reached the hearth, requires an increased amount of heat to keep its remaining sulphur ignited or burning, and for this purpose this auxiliary fire at this point is very essential. This charge of ore, after stirring about one and a half hours, is moved upon either one of the intermediate hearths a of the furnaces A A and is in a short time ready to take salt, as heretofore stated, and be treated in all respects the same as in the operation of the single furnace. Other charges of ore constantly taking its place, it in due time is finished by chloridizing it under the high curved crown, when it is withdrawn from the furnace.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The furnace for roasting, desulphurizin g, or chloridizing ores, as described and shown, with a roof constructed as at c c, and with the The charge which is under the auxpart 0 of said roof nearest to the fire-bOXB and 3. The elevated furnace A with its flue O the part c farthest therefrom, substantially as and fire-box B as described, in combination described. with the furnaces A A constructed with the 2. The chamber of the furnace A constructed roofs c c and fire-boxes B 13 substantially as on a higher plane than the chamber of furnace described.

A, combined with the fire-box B and B and JAMES O. STEWART. connected with the chamber of the furnace A Witnesses:

by flue G, substantially as and for the purpose ANTHONY J. AUGUST,

described. JERRY G. MAHANY. 

